<!DOCTYPE html>
<html>
  <head lang="en">
    <meta charset="UTF-8" />
    <title></title>
    <style>
      * {
        padding: 0;
        margin: 0;
      }

      .wrap {
        width: 300px;
        margin: 100px auto 0;
      }

      table {
        border-collapse: collapse;
        border-spacing: 0;
        border: 1px solid #c0c0c0;
        width: 300px;
      }

      th,
      td {
        border: 1px solid #d0d0d0;
        color: #404060;
        padding: 10px;
      }

      th {
        background-color: #09c;
        font: bold 16px "微软雅黑";
        color: #fff;
      }

      td {
        font: 14px "微软雅黑";
      }

      tbody tr {
        background-color: #f0f0f0;
      }

      tbody tr:hover {
        cursor: pointer;
        background-color: #fafafa;
      }
    </style>
  </head>

  <body>
    <div class="wrap">
      <table>
        <thead>
          <tr>
            <th>
              <input type="checkbox" id="j_cbAll" />
            </th>
            <th>商品</th>
            <th>价钱</th>
          </tr>
        </thead>
        <tbody id="j_tb">
          <tr>
            <td>
              <input type="checkbox" />
            </td>
            <td>iPhone8</td>
            <td>8000</td>
          </tr>
          <tr>
            <td>
              <input type="checkbox" />
            </td>
            <td>iPad Pro</td>
            <td>5000</td>
          </tr>
          <tr>
            <td>
              <input type="checkbox" />
            </td>
            <td>iPad Air</td>
            <td>2000</td>
          </tr>
          <tr>
            <td>
              <input type="checkbox" />
            </td>
            <td>Apple Watch</td>
            <td>2000</td>
          </tr>
          <tr>
            <td>总计：</td>
            <td colspan="2" class="money"></td>
          </tr>
        </tbody>
      </table>
    </div>
    <script>
      var j_cbAll = document.querySelector("#j_cbAll");
      var inps = document.querySelector("#j_tb").querySelectorAll("input");
      var money = document.querySelector(".money");

      j_cbAll.onclick = function () {
        for (var i = 0; i < inps.length; i++) {
          inps[i].checked = j_cbAll.checked;
        }
        var all = getSum();
        money.innerHTML = all;
      };
      for (var i = 0; i < inps.length; i++) {
        inps[i].onclick = function () {
          var flag = true;
          for (var i = 0; i < inps.length; i++) {
            if (!inps[i].checked) {
              flag = false;
              break;
            }
          }
          j_cbAll.checked = flag;
          var all = getSum();
          money.innerHTML = all;
        };
      }
      //   选定的复选框的价钱都加在总计里面
      function getSum() {
        var checks = document.querySelectorAll("#j_tb input:checked");
        var sum = 0;
        for (var i = 0; i < checks.length; i++) {
          var tr = checks[i].parentNode.parentNode;
          sum += +tr.children[tr.children.length - 1].innerHTML;
        }

        return sum;
      }
    </script>
  </body>
</html>
